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• Where to put business logic in MVC design?

  - by BriskLabs Pakistan

  I have created a simple MVC java application that adds records through data forms to a database. my app collects data, it also validates it and stores it. This is because the data is being sourced online from different users. the data is mostly numeric in nature. now on the numeric data being stored into database (SQL server) , i wish that my app should be able to perform computations... and display it. the user is not interested in how computations are done so they must be encapsulated. the user must only be able to view the simple computed data which for example A column data - B Column data / C column data etc... and just display it to the user... i know how to write stored procedures for same but i want a 3 tier app I want the data, that I put into the database as a record, worked upon by performing calculations on it. However, the original data should remain unaffected, while the new data, post-calculations, must be stored as a new entity record into the database. Where should I write the code for this background calculation? As it is the rules and business logic... in a new java beans files ?

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• How to deal with Character body parts from Design to Cocos2d

  - by Edwin Soho

  I'm trying to figure out the pattern the game developers use together with game designers: See the picture below with the independent parts: Questions: 1) Should I create different image parts from different body parts or keep frame by frame animaton? (I know both can be used, but I'm trying to figure what is commonly used in the industry) 2) If I'm going to generate different image parts from different body parts (which is I thing is more logical) how would I export that to Cocos2d (Vector or Bitmap)?

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• Facebook Game database design

  - by facebook-100000781341887

  Hi, I'm currently develop a facebook mafia like PHP game(of course, a light weight version), here is a simplify database(MySQL) of the game id-a <int3> <for index> uid <chr15> <facebook uid> HP <int3> <health point> exp <int3> <experience> money <int3> <money> list_inventory <chr5> <the inventory user hold...some special here, talk next> ... and 20 other fields just like reputation, num of combat... *the number next to the type is the size(byte) of the type For the list_inventory, there have 40 inventorys in my game, (actually, I have 5 these kind of list in my database), and each user can only contain 1 qty of each inventory, therefore, I assign 5 char for this field and each bit of char as 1 item(5 char * 8 bit = 40 slot), and I will do some manipulation by PHP to extract the data from this 5 byte. OK, I was thinking on this, if this game contains 100,000 user, and only 10% are active, therefore, if use my method, for the space use, 5 byte * 100,000 = 500 KB if I use another method, create a table user_hold_inventory, if the user have the inventory, then insert a record into this table, so, for 10,000 active user, I assume they got all item, but for other, I assume they got no item, here is the fields of the new table id-b <int3> <for index> id-a <int3> <id of the user table> inv_no <int1> <inventory that user hold> for the space use, ([id] (3+3) byte + [inv_no] 1 byte ) * [active user] 10,000 * [all inventory] * 40 = 2.8 MB seems method 2 have use more space, but it consume less CPU power. Please comment these 2 method or please correct me if there have another better method rather than what I think. Another question is, my database contain 26 fields, but I counted 5 of them are not change frquently, should I need to separate it on the other table or not? So many words, thanks for reading :)

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• Optimal Database design regarding functionality of letting user share posts by other users

  - by codecool

  I want to implement functionality which let user share posts by other users similar to what Facebook and Google+ share button and twitter retweet. There are 2 choices: 1) I create duplicate copy of the post and have a column which keeps track of the original post id and makes clear this is a shared post. 2) I have a separate table shared post where I save the post id which is a foreign key to post id in post table. Talking in terms of programming basically I keep pointer to the original post in a separate table and when need to get post posted by user and also shared ones I do a left join on post and shared post table Post(post_id(PK), post_content, posted_by) SharedPost(post_id(FK to Post.post_id), sharing_user, sharedfrom(in case someone shares from non owners profile)) I am in favour of second choice but wanted to know the advice of experts out there? One thing more posts on my webapp will be more on the lines of facebook size not tweet size.

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• Design patterns for effects between actors and technology

  - by changelog

  I'm working on my first game, and taking the opportunity to brush up my C++ (I want to make as much of it as portable as I can.) Whilst working on the technology tree and how it affects actors (spaceships, planets, crew, buildings, etc) I can't find a pattern that decouples these entities enough to feel like a clean approach. Just as an idea, here's the type of effects these actors can have on one another (and techs too) An engineer inside a spaceship boosts its shield A hero in a spaceship in a fleet increases morale A technology improves spaceships' travel distance A building in a planet improves its production The best I can come up with is the Observer pattern, and basically manage it more or less manually (when a crew member enters a spaceship, fire the event; when a new building is built in a planet, fire the event, etc etc.) but it seems to be too tightly coupled to me. I would love to get some ideas about how to approach this better.

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• Should we consider code language upon design?

  - by Codex73

  Summary This question aims to conclude if an applications usage will be a consideration when deciding upon development language. What factors if any could be considered upon language writing could be taken into context. Application Type: Web Question Of the following popular languages, when should we use one or the other? What factors if any could be considered upon language writing could be taken into context. Languages PHP Ruby Python My initial thought is that language shouldn't be considered as much as framework. Things to consider on framework are scalability, usage, load, portability, modularity and many more. Things to consider on Code Writing maybe cost, framework stability, community, etc.

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• Need advice on framework design: how to make extending easy

  - by beginner_

  I'm creating a framework/library for a rather specific use-case (data type). It uses diverse spring components, including spring-data. The library has a set of entity classes properly set up and according service and dao layers. The main work or main benefit of the framework lies in the dao and service layer. Developers using the framework should be able to extend my entity classes to add additional fields they require. Therefore I made dao and service layer generic so it can be used by such extended entity classes. I now face an issue in the IO part of the framework. It must be able to import the according "special data type" into the database. In this part I need to create a new entity instance and hence need the actual class used. My current solution is to configure in spring a bean of the actual class used. The problem with this is that an application using the framework could only use 1 implementation of the entity (the original one from me or exactly 1 subclass but not 2 different classes of the same hierarchy. I'm looking for suggestions / desgins for solving this issue. Any ideas?

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• Is Domain Driven Design useful / productive for not so complex domains?

  - by Elijah

  When assessing a potential project at work, I suggested that it might be advantageous to use a domain driven design approach to its object model. The project does not have an excessively complex domain, so my coworker threw this at me: It has been said, that DDD is favorable in instances where there is a complex domain model (“...It applies whenever we are operating in a complex, intricate domain” Eric Evans). What I'm lost on is - how you define the complexity of a domain? Can it be defined by the number of aggregate roots in the domain model? Is the complexity of a domain in the interaction of objects? The domain that we are assessing is related online publishing and content management.

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• Android From Local DB (DAO) to Server sync (JSON) - Design issue

  - by Taiko

  I sync data between my local DB and a Server. I'm looking for the cleanest way to modelise all of this. I have a com.something.db package That contains a Data Helper and couple of DAO classes that represents objects stored in the db (I didn't write that part) com.something.db --public DataHelper --public Employee @DatabaseField e.g. "name" will be an actual column name in the DB -name @DatabaseField -salary etc... (all in all 50 fields) I have a com.something.sync package That contains all the implementation detail on how to send data to the server. It boils down to a ConnectionManager that is fed by different classes that implements a 'Request' interface com.something.sync --public interface ConnectionManager --package ConnectionManagerImpl --public interface Request --package LoginRequest --package GetEmployeesRequest My issue is, at some point in the sync process, I have to JSONise and de-JSONise my data (E.g. the Employee class). But I really don't feel like having the same Employee class be responsible for both his JSONisation and his actual representation inside the local database. It really doesn't feel right, because I carefully decoupled the rest, I am only stuck on this JSON thing. What should I do ? Should I write 3 Employee classes ? EmployeeDB @DatabaseField e.g. "name" will be an actual column name in the DB -name @DatabaseField -salary -etc... 50 fields EmployeeInterface -getName -getSalary -etc... 50 fields EmployeeJSON -JSON_KEY_NAME = "name" The JSON key happens to be the same as the table name, but it isn't requirement -name -JSON_KEY_SALARY = "salary" -salary -etc... 50 fields It feels like a lot of duplicates. Is there a common pattern I can use there ?

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• ASP.NET design not SOLID

  - by w0051977

  SOLID principles are described here: http://en.wikipedia.org/wiki/SOLID_%28object-oriented_design%29 I am developing a large ASP.NET app. The previous developer created a few very large classes each with lots of different purposes. It is very difficult to maintain and extend. The classes are deployed to the web server along with the code behind files etc. I want to share a small amount of the app with another application. I am considering moving all of the classes of the ASP.NET web app to a DLL, so the small subset of functionality can be shared. I realise it would be better to only share the classes which contain code to be shared but because of the dependencies this is proving to be very difficult e.g. class A contains code that should be shared, however class A contains references to classes B, C, D, E, F, G etc, so class A cannot be shared on its own. I am planning to refactor the code in the future. As a temporary solution I am planning to convert all the classes into a single class library. Is this a bad idea and if so, is there an alternative? as I don't have time to refactor at the moment.

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• PyQt design issues

  - by Falmarri

  I've been working on a my first real project using PyQt lately. I've done just a little bit of work in Qt for C++ but nothing more than just messing around. I've found that the Qt python bindings are essentially just a straight port of C++ classes into python, which makes sense. The issue is that this creates a lot of messy, unpythonic code. For example if you look at QAbstractItemModel, there's a lot of hoops you have to go through that forces you to hide the actual python. I was just wondering if there's any intention of writing a python implementation of Qt that isn't necessarily just a wrapper? Either by Nokia or anyone else? I really like Qt but I would love to be able to write more pythonic code. I hope this is OK to ask here. I'm not trying to start a GUI war or anything.

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• Inventory management system design problem

  - by Steve F

  What are the conventions for item batch identifiers in inventory management systems? For example: A retail supermarket can order 'Item X' from either 'Supplier A' or 'Supplier B'. When it completes an order for the item from either supplier, it needs to store the record of the receipt. Inventory quantity for the item is increased upon receipt of the order. However it is also required to store some record of the supplier. Thus some sort of batch identifier is required. This batch identifier will uniquely identify the item received and the supplier from whom it is received. A new batch is created each time items are received in stock (for example, after an order). Hence, for purposes of accounting / auditing, information available to identify an item after it was sold comprises of ITEM_CODE, ITEM_NAME, BATCH_CODE. The BATCH_CODE is unique and is associated with DATE_RECEIVED, SUPPLIER_CODE, QTY_RECEIVED. Is this a complete system specification for the above scenario or has anything significant been left out?

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• How Would You Design This Table?

  - by sooprise

  I have to create a table where each row needs to store 50 number values. Each row will always need to store 50 number values. If this was a smaller number of values, I would just make fields for each of the values, but because there are 50, this approach seems a bit cumbersome (but since it will always be 50 values, maybe this is the correct approach?). Is there a way to store an array of values in a field? This seems like a nice solution, but the concept is almost identical to creating a relational database.

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• How to design brain games [on hold]

  - by samesky

  I will wonder if anybody has some information about designing games for brain improvement. Recently lumosity is into a gear. I guess they research a lot or have experts. But is there any other research paper that is publicly available for designing the brain games ? Any equation or data that can help? Or what characteristics a brain game should have ? I am getting interested on this and search internet a lot, but unfortunately I could not find the core structure of it. It will really a helpful for me if somebody can give some information. Thank you.

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• design an extendible and pluggable business logic flow handler in php

  - by Broncha

  I am working on a project where I need to allow a pluggable way to inject business processes in the normal data flow. eg There is an ordering system. The standard flow of the application is A consumer orders an item. Pays for it and card is authorized. Admin captures the payment. Order is marked as complete and item is shipped. But this process may vary (extra steps in between) for different clients. Say a client would need to validate the location of the consumer before he is presented with a credit card form, OR his policies might require some other processes in between. I am thinking of using State Pattern for processing orders, saving the current state of the order in database, and initializing the state of order from the saved state. I would also need some mechanism, where a small plugin would be able to inject business specific states in the state machine. Am I thinking the right way? Are there already implemented patterns for this kind of situation? I am working with Codeigniter and basically this would mean for me, to redirect to proper controller according to the current state of the order. Like, if the state of the order is unconfirmed then redirect the user to details page and then change the state to pending. If some client would need to do some validation, then register an intermediate state between unconfirmed and pending Please suggest.

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• Client-server application design issue

  - by user2547823

  I have a collection of clients on server's side. And there are some objects that need to work with that collection - adding and removing clients, sending message to them, updating connection settings and so on. They should perform these actions simultaneously, so mutex or another synchronization primitive is required. I want to share one instance of collection between these objects, but all of them require access to private fields of collection. I hope that code sample makes it more clear[C++]: class Collection { std::vector< Client* > clients; Mutex mLock; ... } class ClientNotifier { void sendMessage() { mLock.lock(); // loop over clients and send message to each of them } } class ConnectionSettingsUpdater { void changeSettings( const std::string& name ) { mLock.lock(); // if client with this name is inside collection, change its settings } } As you can see, all these classes require direct access to Collection's private fields. Can you give me an advice about how to implement such behaviour correctly, i.e. keeping Collection's interface simple without it knowing about its users?

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• Layering Design Pattern in Java clean code style

  - by zeraDev

  As a Java developer, I am developing trying to use the clean code rules. But in my team we are facing a concrete problem: We have a business layer offering a service called "createObject", this service makes a lot of operation which can result to problem. E.g: parentObjectDontExist, objectAlreadyExist, dontHaveAuthorizationToCreate, operationFailed... and we want the UI using this service to display different information messages depending which error occurred. In old java dev, we should have create all signed exception type and throw it in createObject. As Clean code says, it is forbidden to use Exception for business logic AND signed exceptions are evil... Why not...But i don't know how to solved this problem and i don't want to use return code. How do you do? Thanks for youre experience return.

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• Android design advice - services & broadcast receivers

  - by basudz

  I'm in the process of learning the Android SDK and creating some projects to get a grasp on the system. The current project I'm working with works just fine but I'd like to get some advice about other ways I can go about designing it. Here's what it needs to do. When a text message is received from a specific number, it should fire off a toast message that repeats at a certain interval for a specific duration. To make this work, I created an SMS BroadcastReceiver and checked the incoming messages for the number I'm looking for. If found, an IntentService would be started that would pull out the interval and duration from saved shared prefs. The IntentService would then fire off a broadcast. The BroadcastReceiver for this would catch it and use the AlarmManager to handle the toast message repetitions. This all works just fine, but I'm wondering if there's a cleaner or more efficient way of going about doing this? Any suggestions or advice?

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• What OO Design to use ( is there a Design Pattern )?

  - by Blundell

  I have two objects that represent a 'Bar/Club' ( a place where you drink/socialise). In one scenario I need the bar name, address, distance, slogon In another scenario I need the bar name, address, website url, logo So I've got two objects representing the same thing but with different fields. I like to use immutable objects, so all the fields are set from the constructor. One option is to have two constructors and null the other fields i.e: class Bar { private final String name; private final Distance distance; private final Url url; public Bar(String name, Distance distance){ this.name = name; this.distance = distance; this.url = null; } public Bar(String name, Url url){ this.name = name; this.distance = null; this.url = url; } // getters } I don't like this as you would have to null check when you use the getters In my real example the first scenario has 3 fields and the second scenario has about 10, so it would be a real pain having two constructors, the amount of fields I would have to declare null and then when the object are in use you wouldn't know which Bar you where using and so what fields would be null and what wouldn't. What other options do I have? Two classes called BarPreview and Bar? Some type of inheritance / interface? Something else that is awesome?

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• Advice needed on Process - Service Design

  - by user99314

  Need some advice from experts on designing a flow. Create a service that will read a csv file which may contain anywhere over 6000+ rows of individual ids as shown in the sample below. Need to read that file and go to oracle database and fetch a vname,vnumber,vid of each id in the csv and then go to document repository i.e. Oracle UCM and download all documents matching vname,vnumber,vid there can be =0 documents for each vname,vnumber,vid and save them on a file system. UCM exposes a webservice to dowload the documents. Finally create a new csv appending the filenames that are downloaded for each id. Need to keep track of any errors but need to make sure to go over the whole ids in the csv to download the documents and skip in case of errors. Need some advice on how to go about designing this as there may be over 6000+ rows in a csv file and looping it and hitting the database for each individual id and then hitting a UCM may be a bit expensive so open for any idea. How to go by designing this solution. Wondering if messaging can be helpful here or offloading process of getting the vname,vnumber,vid to pl/sql packages, creating staging tables etc. Initial csv that contains ids: **ID** 12345a 12s345 3456fr we9795 we9797 Final csv output: **ID Files Downloaded from UCM** 12345a a.pdf,b.doc,d.txt 12s345 a1.pdf,s2.pdf,f4.gif 3456fr b.xls we9795 we9797 x.doc Thanks

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• How can I design multi-threaded application for larger user base

  - by rokonoid

  Here's my scenario, I need to develop a scalable application. My user base may be over 100K, every user has 10 or more small tasks. Tasks check every minute with a third party application through web services, retrieving data which is written in the database, then the data is forwarded to it's original destination. So here's the processing of a small task: while(true){ Boolean isNewInformationAvailable = checkWhetherInformationIsAvailableOrNot(); If(isNewInformationAvailable ==true){ fetchTheData(); writeToDatabase(); findTheDestination(); deliverTheData(); isAvailable =false; } } As the application is large, how should I approach designing this? I'm going to use Java to write it. Should I use concurrency, and how would you manage the concurrency?

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• Would Using a PHP Framework Be Beneficial in My Context?

  - by Fractal

  I've just started work at a small start-up company who mainly uses PHP to develop their front-end apps. I had no prior PHP experience before joining, and this has led to my apps becoming large pieces of spaghetti code. I essentially started by adding code to implement an initial feature, and then continued to hack in more code to implement further features – without much thought for the overall design. The apps themselves output XML to render on small mobile devices. I recently started looking into frameworks that I could use. I reckon an advantage would be that they seem to force developers to modularise their programs using good-practice design patterns. This seems great for someone in my position. The extra functions they provide, for example: interfacing with databases in such a way as to make SQL injection impossible, would be very useful too. The downside I can see is that there will be a lot of overhead for me in terms of the time taken to learn the framework itself (while still getting to grips with PHP itself). I'm also worried that it will be overkill for the scale of the apps we develop. They tend to be programs that interface with a fairly simple back-end DB, and will generate about 5 different XML screens. Probably around 1 or 2 thousand lines of code. The time it takes just to configure the frameworks may not be worth it. The final problem I can see is that developers in the company – who have to go over my code, and who do not know the PHP framework I may use – will have a much harder time understanding it. Given those pros and cons, I'm still not sure on what the best course of action will be; so any advice will be greatly appreciated.

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• Checking preconditions or not

  - by Robert Dailey

  I've been wanting to find a solid answer to the question of whether or not to have runtime checks to validate input for the purposes of ensuring a client has stuck to their end of the agreement in design by contract. For example, consider a simple class constructor: class Foo { public: Foo( BarHandle bar ) { FooHandle handle = GetFooHandle( bar ); if( handle == NULL ) { throw std::exception( "invalid FooHandle" ); } } }; I would argue in this case that a user should not attempt to construct a Foo without a valid BarHandle. It doesn't seem right to verify that bar is valid inside of Foo's constructor. If I simply document that Foo's constructor requires a valid BarHandle, isn't that enough? Is this a proper way to enforce my precondition in design by contract? So far, everything I've read has mixed opinions on this. It seems like 50% of people would say to verify that bar is valid, the other 50% would say that I shouldn't do it, for example consider a case where the user verifies their BarHandle is correct, but a second (and unnecessary) check is also being done inside of Foo's constructor.

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• Confused about implementing Single Responsibility Principle

  - by HichemSeeSharp

  Please bear with me if the question looks not well structured. To put you in the context of my issue: I am building an application that invoices vehicles stay duration in a parking. In addition to the stay service there are some other services. Each service has its own calculation logic. Here is an illustration (please correct me if the design is wrong): public abstract class Service { public int Id { get; set; } public bool IsActivated { get; set; } public string Name { get; set } public decimal Price { get; set; } } public class VehicleService : Service { //MTM : many to many public virtual ICollection<MTMVehicleService> Vehicles { get; set; } } public class StayService : VehicleService { } public class Vehicle { public int Id { get; set; } public string ChassisNumber { get; set; } public DateTime? EntryDate { get; set; } public DateTime? DeliveryDate { get; set; } //... public virtual ICollection<MTMVehicleService> Services{ get; set; } } Now, I am focusing on the stay service as an example: I would like to know at invoicing time which class(es) would be responsible for generating the invoice item for the service and for each vehicle? This should calculate the duration cost knowing that the duration could be invoiced partially so the like is as follows: not yet invoiced stay days * stay price per day. At this moment I have InvoiceItemsGenerator do everything but I am aware that there is a better design.

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• A better alternative to incompatible implementations for the same interface?

  - by glenatron

  I am working on a piece of code which performs a set task in several parallel environments where the behaviour of the different components in the task are similar but quite different. This means that my implementations are quite different but they are all based on the relationships between the same interfaces, something like this: IDataReader -> ContinuousDataReader -> ChunkedDataReader IDataProcessor -> ContinuousDataProcessor -> ChunkedDataProcessor IDataWriter -> ContinuousDataWriter -> ChunkedDataWriter So that in either environment we have an IDataReader, IDataProcessor and IDataWriter and then we can use Dependency Injection to ensure that we have the correct one of each for the current environment, so if we are working with data in chunks we use the ChunkedDataReader, ChunkedDataProcessor and ChunkedDataWriter and if we have continuous data we have the continuous versions. However the behaviour of these classes is quite different internally and one could certainly not go from a ContinuousDataReader to the ChunkedDataReader even though they are both IDataProcessors. This feels to me as though it is incorrect ( possibly an LSP violation? ) and certainly not a theoretically correct way of working. It is almost as though the "real" interface here is the combination of all three classes. Unfortunately in the project I am working on with the deadlines we are working to, we're pretty much stuck with this design, but if we had a little more elbow room, what would be a better design approach in this kind of scenario?

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